Biggest issue is basically that meteor has an ecosystem of dependencies that need their source code modified to work with Meteor, Meteor also relies entirely on global variables and a number of other uglies.

I have been involved professionally with developing two medium-large applications on Meteor, and it's terrifying.(first time was when it was in alpha, so I forgave it, second time out of alpha, and it's almost worse).

I think that HN is run from this https://github.com/arclanguage/anarki or something similar. (there's a run-news script in there which IIRC instantiates something a whole lot like HN).